MODESTO, California (CNN) --A judge decided Tuesday to bind Scott Peterson over for trial on murder charges in the deaths of his pregnant wife, Laci Peterson, and their unborn child.

The decision -- on the 12th day of Peterson's preliminary hearing -- quickly followed the end of the prosecution presentation and the defense decision not to call witnesses -- a move that kept Peterson's ex-mistress, Amber Frey, from testifying before the actual trial.

Peterson's next court appearance is set for December 3, when he will face arraignment in Stanislaus County court and when the judge will consider a defense request to move the trial to another county.

Peterson has pleaded not guilty. If convicted for the murders of his wife and their unborn child, Peterson, 31, could be sentenced to death.

The prosecution called two investigators Tuesday morning, including one who recorded Peterson's conversations with Frey starting a week after Christmas Eve, the day officials believe Laci Peterson's pregnant body was dumped in San Francisco Bay.

Detective Jon Buehler quoted from the transcript of several calls and from his interviews with Frey.

Frey told police that Peterson explained to her on December 9 that he had "lost" his wife and tearfully apologized for not telling her sooner about his marriage, Buehler testified. Frey said she comforted Peterson as he sat on her sofa, crying and holding her hand, Buehler said.

Buehler also showed the court pictures of Frey and Peterson together at a Christmas party just a week before Laci Peterson's disappearance.

Buehler said he began recording Peterson's calls with Frey beginning on December 30, when she first came forward to investigators about their relationship.

In a January 6 recorded call, Frey asked Peterson to explain why he lied to her about his wife, he said.

Under cross-examination by defense lawyer Mark Garagos, Beuhler conceded that Peterson never tried to dissuade Frey from going to police with her story. In one recorded call Peterson told Frey it was her decision to make, Buehler said.

Steven Jacobson, an investigator with the Stanislaus County district attorney's office, testified Tuesday morning about his examination of cell phone records showing at least 241 calls between Peterson and Frey starting November 19 and ending February 19.

None of the calls were on December 24. Peterson told police he went fishing that day and returned to discover his wife was missing.

Jacobson said phone records were used to track Peterson's movements that day, starting at 10:08 a.m. when he was at or near his home and continuing as he drove to the Berkeley Marina about 80 miles away. Testimony earlier in the hearing said Peterson claimed to have left his home around 9:30 a.m. Peterson told police he last saw his wife mopping the floor at that time.

Phone records showed a call made from Peterson's cell phone at or near the Marina at 2:12 p.m. that day, followed by a flurry of calls from the neighborhood of his home starting at 5:44 p.m., Jacobson said. It was at this time Peterson said he realized his wife was missing and he began calling friends, relatives and neighbors. He also called 911 at 6:10 p.m., Jacobson said.

Detective Buehler also testified that when Peterson' was arrested on April 18 his car was loaded with camping gear, including rope, an ax, folding knives, a hammock, a water purifier and a fishing pole.

Peterson also had $15,000 cash, four cell phones and his brother's driver's license, he testified.

During cross-examination, defense lawyer Mark Geragos suggested Peterson intended to use his brother's driver's license to get a discount at a golf course.